U.S. patent number 5,410,130 [Application Number 08/230,291] was granted by the patent office on 1995-04-25 for heating and temperature cycling.
This patent grant is currently assigned to Ericomp, Inc.. Invention is credited to Zachary L. Braunstein.
United States Patent |
5,410,130 |
Braunstein |
April 25, 1995 |
Heating and temperature cycling
Abstract
A heating element having a pair of terminals for being coupled
to a source of electric current. The heating element includes a
path arranged in a field having outer path elements and inner path
elements. The outer path elements are in the form of at least one
row of a repeated alternating wave of a first predetermined
amplitude and pitch. The row substantially surrounding the
perimeter of the field and the inner path elements is primarily in
the form of a repeated alternating wave of a second predetermined
amplitude and pitch. The second amplitude is substantially greater
than that of the first amplitude and the second pitch is less than
the first pitch. A sample heating device includes a base, four side
walls extending from the base and a sample holding plate for
holding sample vials. The sample holding plate, the base, and the
side walls define a chamber. The sample vials are positioned within
the chamber. The device also includes a first heating device for
heating the chamber and the sample vials positioned therein. A
temperature cycling apparatus includes a sample heating device as
discussed above, and the sample heating device. The base of the
sample heating device is positioned over the first fan and the
first fan blows air toward the heating device.
Inventors: |
Braunstein; Zachary L. (San
Diego, CA) |
Assignee: |
Ericomp, Inc. (San Diego,
CA)
|
Family
ID: |
22864635 |
Appl.
No.: |
08/230,291 |
Filed: |
April 20, 1994 |
Current U.S.
Class: |
219/521;
219/386 |
Current CPC
Class: |
B01L
7/52 (20130101) |
Current International
Class: |
B01L
7/00 (20060101); H05B 003/30 () |
Field of
Search: |
;219/521,385,386 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Walberg; Teresa J.
Attorney, Agent or Firm: McAulay Fisher Nissen Goldberg
& Kiel
Claims
What is claimed is:
1. A sample heating device comprising:
an open container having a bottom portion and a side wall
portion;
a sample holding plate disposed in a portion of said container,
said plate having openings therein for receiving sample vials, said
sample holding plate and said bottom portion and side wall portion
of said container defining a chamber, said plate adapted to hold
the sample vials so that a portion of each vial is positioned
within the chamber; and
first heating means for heating the chamber and the sample vials
positioned therein by both conduction and radiation.
2. The sample heating device of claim 1 wherein said first heating
means is affixed to said bottom portion of the container, the
sample vials being positioned to contact said bottom portion.
3. The sample heating device of claim 2 wherein said first heating
means includes a periphery, an inner portion, and means for
providing greater heating capacity at said periphery than at said
inner portion.
4. The sample heating device of claim 1 wherein said side wall
portion comprises four side walls; wherein said bottom portion is
substantially rectangular or square shaped and wherein said first
heating means is substantially rectangular or square in shape and
is affixed to said bottom portion.
5. The sample heating device of claim 1 further comprising
regulating means for regulating the temperature within said
chamber.
6. The sample heating device of claim 5 wherein said regulating
means includes a thermoelectric switch, said thermoelectric switch
for monitoring the temperature within the chamber and disconnecting
power supplied to said first heating device when the temperature
within the container exceeds a predetermined value.
7. A sample heating device comprising:
an open container having a bottom portion and a side wall
portion;
a sample holding plate disposed in a portion of said container,
said plate having openings therein for receiving sample vials, said
sample holding plate and said bottom portion and side wall portion
of said container defining a chamber, said plate adapted to hold
the sample vials so that a portion of each vial is positioned
within the chamber; and
first heating means for heating the chamber and the sample vials
positioned therein,
wherein said first heating means is affixed to said bottom portion,
the sample vials being positioned to contact said bottom portion,
and
wherein said first heating means includes a pair of terminals for
being coupled to a source of electric current and a heating
element, said heating element having a path arranged in a field
having outer path elements and inner path elements, said outer path
elements being in the form of at least one row of a repeated
alternating wave of a first predetermined amplitude and pitch, said
row substantially surrounding the periphery of the field, said
inner path elements being primarily in the form of a repeating
alternating wave of a second predetermined amplitude and pitch,
said second amplitude being substantially greater than that of said
first amplitude and said second pitch being less than said first
pitch.
8. A sample heating device comprising;
an open container having a bottom portion and a side wall
portion;
a sample holding plate disposed in a portion of said container,
said plate having openings therein for receiving sample vials, said
sample holding plate and said bottom portion and side wall portion
of said container defining a chamber, said plate adapted to hold
the sample vials so that a portion of each vial is positioned
within the chamber;
first heating means for heating the chamber and the sample vials
positioned therein; and
a second heating means for heating said chamber, said second
heating means being mounted to said sample holding plate for
providing evaporation control.
9. The sample heating device of claim 8 wherein said bottom portion
includes recesses for receiving tips of the sample vials positioned
within the chamber.
10. The sample heating device of claim 8 wherein said second
heating means includes openings corresponding to the openings of
said sample holding plate and wherein said second heating means
includes means for providing greater capacity heating at its
periphery than at its inner portion.
11. The sample heating device of claim 10 wherein said second
heating means includes a heating element which substantially
surrounds each opening of said second heating means and wherein
said element includes a pair of terminals for being coupled to a
source of electrical energy.
12. The sample heating device of claim 8 further comprising means
for regulating the temperature within said container.
13. The sample heating device of claim 12 wherein said regulating
means includes a thermoelectric switch, said thermoelectric switch
for monitoring the temperature within the chamber and disconnecting
power supplied to said first and second heating device when the
temperature within the chamber exceeds a predetermined value.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to heating and temperature cycling.
More specifically, the present invention is drawn to an apparatus
for heating samples and a temperature cycling apparatus
incorporating the device for heating the samples.
2. Description of the Related Art
During the handling of various chemical samples, it is often
necessary to heat the samples to effect a desired reaction or
result. In addition, it is often desirable to subject the chemical
samples to temperature cycling through a range of hot and cold
temperatures.
Devices for heating chemical samples currently employ a solid block
of aluminum having wells drilled therein to receive vials which
hold chemical samples. The vials holding the samples are ordinarily
made from a plastic such as polypropelene. The wells drilled in the
aluminum block have close tolerances to the outer dimensions of the
plastic sample vials so as to provide significant contact between
the outer surfaces of the vials and the aluminum block.
Furthermore, the tight tolerances reduce the losses in heat during
transfer from the block to the vials and chemical samples.
The solid aluminum block is heated which, in turn, heats the
chemical samples contained in the tubes that are positioned in the
wells of the solid block. The aluminum block is heated using an
electric heater having uniform heat dissipation. Due to the mass of
the solid block, the electric heater requires a power rating of
approximately 1000 Watts. The solid block arrangement provides for
substantially uniform heating of the samples held therein.
When electric heating is employed, the heating element which is
placed into contact with the solid aluminum block has decreased
heat transfer characteristics near the edges of the electric
heating element. As a result, the heat transferred to the solid
block is not uniform and heating efficiency of the solid block is
reduced. Furthermore, the current required to operate the electric
heater is substantial, thus increasing operating costs.
In order to prevent evaporation of the samples contained in the
plastic tubes, heated covers are placed over the plastic tubes.
These covers are heated to a temperature which exceeds the
temperature to which the samples contained in the tubes are heated.
As a result, evaporation of the sample is prevented. However, since
the tubes are normally filed to approximately 1/3 of capacity,
separation of the sample contained within the tube often occurs.
More specifically, the sample travels up the walls of the plastic
tube until it is repulsed by a higher temperature level. The
greater the distance between the sample and the higher temperature
gradient, the further the sample travels in the tube. As a result,
therefore, the sample vials must be subjected to a centrifuge to
gather the samples.
When the solid aluminum block is incorporated into a temperature
cycling arrangement, the heated block containing the sample is
normally immersed in a cold bath to reduce the temperature of the
block and the chemical samples held therein.
The drawbacks associated with the solid block construction include
high manufacturing cost, high weight, and complicated cooling
methods to achieve acceptable cooling times. The high weight of the
solid block also proves inconvenient if the solid block is to be
placed in a cold bath to effect cooling.
Accordingly, it is an object of the present invention to provide a
light weight sample holding device which provides good heat
transfer characteristics to the samples held therein. It is a
further object of the present invention to minimize separation of
chemical samples held within tubes associated with the sample
holding device. An additional objective of the present invention is
to provide a light weight and small size temperature chamber to
effect temperature cycling of chemical samples. It is also an
object of the present invention to provide convenient and effective
cooling of samples when subjected to temperature cycling. An added
object is to provide an improved heating element construction which
increases heat transfer characteristics near the edges of the
heating element.
SUMMARY OF THE INVENTION
A heating element having a pair of terminals for being coupled to a
source of electric current. The heating element includes a path
arranged in a field having outer path elements and inner path
elements. The outer path elements are in the form of at least one
row of a repeated alternating wave of a first predetermined
amplitude and pitch. The row substantially surrounding the
perimeter of the field and the inner path elements is primarily in
the form of a repeated alternating wave of a second predetermined
amplitude and pitch. The second amplitude is substantially greater
than that of the first amplitude and the second pitch is less than
the first pitch.
A sample heating device includes a base, four side walls extending
from the base and a sample holding plate for holding sample vials.
The sample holding plate, the base, and the side walls define a
chamber. The sample vials are positioned within the chamber. The
device also includes a first heating device for heating the chamber
and the sample vials positioned therein.
A temperature cycling apparatus includes a sample heating device as
discussed above. The base of the sample heating device is
positioned over the first fan and the first fan blows air toward
the heating device.
For a better understanding of the present invention, reference is
made to the following description and drawings, while the scope of
the invention will be pointed out by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a sample heating device
according to the present invention.
FIG. 2 is an illustration of a heating element which is
incorporated into the base of the embodiment disclosed in FIG.
1.
FIG. 3 is a view similar to FIG. 1, illustrating a sample heating
device which includes a second heating element.
FIG. 4 is an illustration similar to FIG. 2, for the second heating
element illustrated in FIG. 3.
FIG. 5 illustrates an alternate embodiment to the second heating
element disclosed in FIG. 4.
FIG. 6 is an embodiment similar to that shown in FIG. 3 and
illustrates a modified base portion for receiving the tips of the
sample vials.
FIG. 7 illustrates a temperature cycling chamber according to the
present invention which incorporates the sample heating device
illustrated in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, heating device 10 according to the present
invention includes base portion 12, side walls 14, 16, sample
holding plate 18, and positioning means 20 for positioning holding
plate 18. In one embodiment side walls 14, 16 may be replaced by a
cylindrical side wall portion. Accordingly, the external geometry
of heating device 10 is not limited to that illustrated in FIG.
1.
Base portion 12 includes inner wall 22, outer wall 24, and heating
element 26. Base portion 12 may also include thermo-conductive pad
28 which has a high coefficient of conductivity to increase
uniformity of the heat dispersed by heating element 26. In one
embodiment, thermo-conductive pad 28 has a thermal conductivity of
approximately 3.85 W/(m.K). Preferably, heating element 26 is high
pressure/high temperature glued to the bottom of inner wall 22. The
temperature range at which heating element 26 operates is between
ambient temperature and 140.degree. C. Thermo-breaker switch 37 may
be positioned in communication with chamber 36. The temperature
limit of thermo-breaker switch 37 should be selected so that power
is not provided to heating element 26 when it reaches a temperature
near its upper limit. In one embodiment, the temperature limit of
thermo-breaker switch 37 is selected, accounting for the
temperature gradient within chamber 36, at approximately
110.degree. C. Heating element 26 is also referred to herein as
first heating means.
Preferably, heating device 10 is constructed from aluminum. To
prevent warping of inner wall 22, bottom portion 12 is constructed
as follows: inner wall 22 and outer wall 24 are constructed from
AL5052; both inner wall 22 and outer wall 24 are approximately 0.06
inches thick; and, thermo-conductive pad 28 is approximately 0.007
inches thick.
Sample holding plate 18 includes a series of holes 30 for receiving
and positioning vials 32 having chemical samples 34 therein. Sample
holding plate 18 is positioned within heating device 10 by
positioning means 20. Preferably, positioning means 20 permits
horizontal positioning of sample holding plate 18 with respect to
inner wall 22. Positioning means 20 may include pegs, clips, pins,
screws, etc., which attach to side walls 14, 16. Furthermore,
positioning means 20 may include standoffs connected to inner wall
22. Multiple sample holding plates 18 may be positioned within
heating device 10.
Sample holding plate 18, side walls 14, 16 and inner wall 22 define
chamber 36. Heating element 26 heats inner wall 22. Inner wall 22
heats sample vial 32 as a result of direct contact between the tip
of sample vial 32 and inner wall 22. In addition, the air within
chamber 36 is heated due to the heat which radiates from the
surface of inner wall 22. Holes 30 in sample holding plate 18 are
sized so as to have minimal space through which air within chamber
36 can escape once sample vials 32 are inserted therethrough.
Accordingly, chamber 36 effectively operates as a heating chamber,
with little heated air escaping through openings 30. Preferably,
openings 30 are sized to a diameter which is approximately 0.003
inches to 0.005 inches larger than the outer diameter of sample
vial 32.
By employing chamber 36, the weight of the heating device 10 is
approximately one eighth of the weight of the solid block
construction. Furthermore, the reduced weight of heating device 10
provides the operator with greater control over the temperature to
which samples 34 are subjected.
The edges of heating element 26 are designed so that the density of
the power dissipated near the edges is increased approximately 10%
from the power dissipated near the center of heating element 26.
The power dissipation density may be increased linearly,
parabolically, or according to some other mathematical equation.
The increased power dissipation density begins at a location a
predetermined distance from the edges of heating element 26. The
predetermined distance may be 20% of the distance measured between
the center of heating element 26 and each edge. The maximum power
dissipation density, therefore is adjacent the edges of heating
element 26
Referring to FIG. 2, one embodiment of heating element 26 is shown
in greater detail. Heating element 26 includes a pair of terminals
38, 40 for being coupled to a source of electric current (not
shown). Heating element 26 has a path arranged in a field having
outer path elements 42, 44 and inner path elements 46. The outer
path elements 42, 44 are in the form of at least one row of a
repeated alternating wave of a first predetermined amplitude and
pitch. The row substantially surrounds the perimeter of the field.
The inner path elements 46 are primarily in the form of a repeated
alternating wave of a second predetermined amplitude and pitch. The
second amplitude is substantially greater than that of the first
amplitude and the second pitch is less than the first pitch.
Terminals 38, 40 may be connected to a power source (not shown)
through thermo-breaker switch 37 to cause heating. Outer path
elements 42 and 44, as illustrated in FIG. 2, increase heating
along the edges of heating element 26 by approximately 10% from
those heating elements which are generally available in the art.
The power rating of heating element 26 is approximately 530 Watts.
Heating element 26 may be constructed from KAPTON.TM., or mica,
silicone rubber. Preferably, element 26 is substantially flat.
Referring to FIG. 3, heating device 48, according to a second
embodiment of the present invention, is substantially similar to
the device illustrated in FIG. 1. Accordingly, the identification
numerals for elements previously described remain the same. The
significant difference between the embodiment shown in FIG. 3 and
that of FIG. 1 is that sample holding plate 18 of FIG. 1 has been
replaced with sample holding plate 50 in the embodiment shown in
FIG. 3. Sample holding plate 50 includes upper plate 52 having
through holes 54 therein for receiving sample vials 32. Upper
holding plate 52 may be constructed from AL5052 and may have a
thickness of approximately 0.06 inches. Sample holding plate 50
also includes second heating element 56 having through holes 58
which align with through holes 54 of upper plate 52. The through
hole pairs 54, 58 are for receiving sample vials 32. Second heating
element 56 is also referred to herein as second heating means.
Second heating element 56, similar to first heating element 26,
provides increased heating at its periphery.
Sample holding plate 50 may be employed as an evaporation control
device by maintaining the temperature of sample holding plate 50 at
a temperature higher than the temperature of sample 34. In this
fashion, therefore, a temperature gradient is created in chamber 36
whereby the temperature at sample holding plate 50 is maintained at
a temperature which is approximately 10 degrees higher than that of
sample 34. By providing the higher temperature above, but close to,
the surface of sample 34, the travel of the sample 34 within sample
vial 32 is reduced and the uniformity of sample 34 is
maintained.
Thermo-breaker switch 37 may be connected in parallel to both
heating element 26 and second heating element 56 to provide
temperature range protection.
Positioning means 20 may be moveable within device 48 to adjust the
positioning of sample holding plate 50. Accordingly, the distance
between the surface of sample 34 and holding plate 50 may be
adjusted as needed. Furthermore, it is conceivable that more than
one sample holding plate may be positioned within device 48. In
this fashion, therefore, sample holding plate 50 may be used to
provide additional heating at a position below the surface of
sample 34. A second sample holding plate may then be positioned
above the surface of sample 34 to act as an evaporation control
device. Since multiple chambers would be created, it is conceivable
that thermo-breaker switches be provided in each chamber.
FIG. 4 is an embodiment illustrating second heating element 56
having 60 wells for receiving 60 sample vials 32, each having a
volume of 0.6 milliliters. Second heating element 56 includes
terminals 60, 62 which are interconnected by conductive heating
trace 64. The power rating of the embodiment shown in FIG. 4 is
approximately 183 Watts. Second heating element 56 provides for
uniformity and is capable of generating heat levels required to
effect evaporation control.
Furthermore, due to the relatively small mass of heating device 48,
a light weight heating device is provided. In addition, the
operator may accurately control the temperature of the sample 34
while preventing evaporation of and reducing the travel of sample
34.
FIG. 5, illustrates an alternate second heating element 66 which
provides for 96 wells for holding 96 sample vials 32, each having a
volume of 0.2 milliliters. Second heating element 66 includes
terminals 68, 70 which are interconnected by conductive heating
trace 72. Heating element 66 has a power rating of approximately
180 Watts.
The heating speed of heating device 48 is approximately 10% faster
than the heating speed of heating device 10, due to the
incorporation of second heating element 56.
FIG. 6 illustrates heating device 74 according to a third
embodiment of the present invention. Heating device 74 is
substantially similar to the embodiment illustrated in FIG. 3.
Accordingly, the same identification numerals are employed for the
elements previously described. Inner wall 22 of FIG. 3 has been
replaced with inner wall 76 as illustrated in FIG. 6. Inner wall 76
includes indentations 78 for receiving the tips of sample vials 32.
In this fashion, indentations 78 provide a larger surface area over
which contact with the sample vials 32 is provided. Furthermore,
the tips of sample vials 32, and therefore, samples 34 are
positioned closer to heating element 26. As a result, increased
heating efficiency is provided.
In one embodiment, inner wall 76 is constructed from 0.06 inch
thick AL5052. Indentations 78 are contoured to receive tips of
sample vials 32 and are approximately 0.02 inches deep.
FIG. 7 is an illustration of a temperature cycling chamber 80 which
includes side walls 82, 84, base 86, and lid 88. Lid 88, sidewalls
82, 84 and base 86 define chamber 90. In an alternate embodiment,
side walls 82, 84 may be replaced by a cylindrical side wall
portion.
Heating apparatus 48, as disclosed in reference to FIG. 3, is
suspended within chamber 90 by support members 92, 94. While
heating apparatus 48 is used for discussion purposes, any of the
heating devices disclosed herein may be employed with temperature
cycling chamber 80. Support members 92, 94 are attached to
extensions 96, 98 of side walls 14, 16, respectively. Heating
apparatus 48 operates as previously disclosed. In order to effect
temperature cycling, means for cooling the samples is included in
temperature cycling chamber 80. First fan 100 is positioned below
heating element 26 and, during operation, translates air into
contact with bottom portion 12 to effect cooling. An air intake
communicates with first fan 100 through base 86. Preferably, first
fan 100 is rated at approximately 110 cubic feet/minute. First fan
100 is a component of first air circulation means which includes a
control device 108 and a drive mechanism 110.
Second fan 102 may be provided to pull air from chamber 36. In
addition, second fan 102 pulls air from chamber 90, around side
walls 14, 16, to further cool heating apparatus 48. Fan 102 may be
connected to lid 88 through connecting members 104, 106 so that the
exhaust of second fan 102 circulates within chamber 90. Preferably,
second fan 102 is rated at approximately 80 cubic feet/minute.
Second fan 102 is a component of second air circulation means 110
which includes a control device 112 and a drive mechanism 114.
Fans 100, 102 provide a cooling speed in excess of 1.2.degree.
Celsius/second.
A control algorithm may be employed to monitor heating of samples
34 and chamber 36. Referring to FIG. 1, a thermocouple 33 may be
inserted within sample vial 32 to provide information relating to
the temperature of sample 34. The temperature data of sample 34 may
be sent to a monitor or a central processing unit (not shown).
A second thermocouple 35 may be used to provide data relating to
the temperature of chamber 36. Second thermo couple 35 may be of
the washer type. The temperature data provided by second
thermocouple 35 may be sent to a monitor or a central processing
unit (not shown).
The central processing unit may employ a algorithm utilizing the
data supplied by thermo couples 33, 35 to achieve the necessary
energy during heating. As a result, rapid and accurate heating of
sample 34 may be insured. The algorithm also controls the energy
supplied to fans 100, 102 to control the cooling of sample 34.
EXAMPLES
A number of tests were performed on a variety of embodiments of the
temperature cycling apparatus 80, including those which incorporate
heating devices 10 and 48 to evaluate the heating and cooling
speeds effected by apparatus 80.
1. The first device tested is constructed as a temperature cycling
device 80 having only one fan 100 mounted on base 86 to effect
cooling. The temperature cycling device incorporates a heating
device substantially similar to that disclosed in FIG. 1. The
temperature cycling device has a capacity of 60 sample vials, each
having a volume of approximately 0.6 milliliters. The following
results are obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.7.degree. C./s, the cooling speed is
0.6.degree. C./s, and the average temperature change rate is
0.65.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.1.degree. C./s, the cooling speed
is 0.7.degree. C./s, and the average temperature change rate is
0.4.degree. C/s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C., based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU1## 2. The second device tested is
constructed as a temperature cycling device 80 having only one fan
100 mounted on base 86 to effect cooling. The temperature cycling
device incorporates a heating device substantially similar to that
disclosed in FIG. 3. Sample holding plate 50 is positioned
approximately 0.1 inches from the tops of sample vials 32. The
temperature cycling device has a capacity of 60 sample vials, each
having a volume of approximately 0.6 milliliters. The following
results are obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.8.degree. C./s, the cooling speed is
0.6.degree. C./s, and the average temperature change rate is
0.7.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.5.degree. C./s, the cooling speed
is 0.6.degree. C./s, and the average temperature change rate is
0.55.degree. C./s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C., based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU2## 3. The third device tested is
constructed as a temperature cycling device 80 having fans 100,
102. Fan 102 was mounted approximately 0.05 inches from the tops of
sample vials 32. Fan 102 has 1.0 inch diameter and is rated at 80
cubic feet/minute. The temperature cycling device incorporates a
heating device substantially similar to that disclosed in FIG. 1.
The temperature cycling device has a capacity of 60 sample vials,
each having a volume of approximately 0.6 milliliters. The
following results are obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.7.degree. C./s, the cooling speed is
1.1.degree. C./s, and the average temperature change rate is
0.8.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.1.degree. C./s, the cooling speed
is 1.3.degree. C./s, and the average temperature change rate is
0.7.degree. C./s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C., based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU3## 4. The fourth device tested is
constructed as a temperature cycling device 80 having only one fan
100 mounted on base 86 to effect cooling. The temperature cycling
device incorporates a heating device substantially similar to that
disclosed in FIG. 1. The temperature cycling device has a capacity
of 96 sample vials, each having a volume of approximately 0.2
milliliters. The following results are obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.8.degree. C./s, the cooling speed is
0.7.degree. C./s, and the average temperature change rate is
0.75.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.5.degree. C./s, the cooling speed
is 0.8.degree. C./s, and the average temperature change rate is
0.65.degree. C/s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C. based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU4## 5. The fifth device tested is
constructed as a temperature cycling device 80 having only one fan
100 mounted on base 86 to effect cooling. The temperature cycling
device incorporates a heating device substantially similar to that
disclosed in FIG. 3. Sample holding plate 50 is positioned
approximately 0.35 inches from the tops of sample vials 32. The
temperature cycling device has a capacity of 96 sample vials, each
having a volume of approximately 0.2 milliliters. The following
results were obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.8.degree. C./s, the cooling speed is
0.7.degree. C./s, and the average temperature change rate is
0.75.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.6.degree. C./s, the cooling speed
is 0.7.degree. C./s, and the average temperature change rate is
0.65.degree. C./s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C. based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU5## 6. The sixth device tested is
constructed as a temperature cycling device 80 having fans 100,
102. Fan 102 is mounted approximately 0.35 inches from the tops of
sample vials 32. Fan 102 has a 1.0 inch diameter and is rated at 80
cubic feet/minute. The temperature cycling device incorporates a
heating device substantially similar to that disclosed in FIG. 1.
The temperature cycling device has a capacity of 96 sample vials,
each having a volume of approximately 0.2 milliliters. The
following results were obtained:
a) For a temperature range from 20.degree. C. to 90.degree. C., the
heating speed obtained is 0.8.degree. C./s, the cooling speed is
1.1.degree. C./s, and the average temperature change rate is
0.9.degree. C./s.
b) For a temperature range from 90.degree. C. to 100.degree. C.,
the heating speed obtained is 0.5.degree. C./s, the cooling speed
is 1.3.degree. C./s, and the average temperature change rate is
0.9.degree. C./s.
In sum, therefore, over a temperature range from 20.degree. C. to
100.degree. C., based on 10.degree. C. increments, the heating and
cooling speeds are: ##EQU6##
While preferred embodiments of the present invention have been
shown and described it will be understood by those skilled in the
art that various changes and modifications could be made without
varying from the scope of the present invention.
* * * * *